OK, this is a progressive bet, 2 to 18 numbers bet.
For each steet hit, bet the two unhit numbers in that particular street, up to maximum 18 numbers bet. Stop and restart after each hit
So, the bet will be 2+2+2+2+2+2+2+2+2=18 numbers in a progressive bet.
Progression 1 1 1 1 1 2 3 5 10 20 40...and so on. Doesn't matter if a number repeats or not (or if zero hits) 2u are always bet after the 5th spin, and progression starts from there.
Higest step in progression from my tests was the 11th step (40u), so a high table-limit for straight ups and a bankroll of minumum 1000u is required. It's risk vs reward...
First test was played with 1u bets.